A brief discussion of the terminology and context of certain terms used herein is believed to be conducive to a more complete understanding of the present invention. Any reference herein to 802.11 is to be understood as referring to IEEE 802.11.
802.11n can be viewed as an extension to 802.11a, and was deliberated upon by the 802.11 Task Group “n”, late in the year 2003 to address modifications to the PHY layer and Medium Access control Layer (PHY/MAC) to ensure a delivery of a maximum of even 600 megabits per second (Mbps) at PHY level.
Cordics is an algorithm for calculating hyperbolic and trigonometric functions (including Sine-Cosine functions, magnitude and phase). Known in binary form since at least 1959, in the presently known applications is faster than a hardware multiplier, and is well suited to hardware, and needs no multipliers.
WLANs are relevant in the context of IEEE 802.11n standard for processing data. The main attraction of WLANs is their flexibility. They can extend access to local area networks, such as corporate intranets, as well as support broadband access to the Internet—particularly at “hot spots,” public venues which users tend to access. WLANs can provide quick, easy wireless connectivity to computers, machinery, or systems in a local environment where a fixed communications infrastructure does not exist or where such access may not be permitted. These WLAN hosts can be stationary, handheld, or even mounted on a moving vehicle. Bandwidth considerations have thus far been rather secondary in WLAN design and implementation in that the original 802.11 standard allowed a maximum channel bit rate of only 2 megabits per second, while the current 802.11 b standard supports an 11 Mbps maximum rate. However, the widespread deployment of 802.11a and 802.11g standards, which allow a bit rate of up to 54 Mbps, are conducive to new types of mobile applications, including m-commerce transactions and location-based services.
Current IEEE 802.11 wireless local area network (WLAN) standard products can provide up to 54 Mbps raw transmission rate, while non-standard WLAN products with 108 Mbps are known in the market, and the next generation WLAN might provide much higher transmission rates. However, originally the MAC (Medium Access Control) was designed for lower data rates, such as 1-2 Mbps, and it is relatively not an efficient MAC. Furthermore, a theoretical throughput limit exists due to overhead and limitations of physical implementations and therefore increasing the transmission rate may not help significantly, whereby, designing efficient MAC strategies becomes critical and useful. Efficient and improved new MACs assist not only current IEEE 802.11 standards (.11a/.11b/.11g), but also the next generation WLAN with higher speed and higher throughput, especially in IEEE 802.11n applications.
IEEE 802.11n as a new standardization effort is an amendment to IEEE 802.11 standards that is capable of much higher throughputs, with a maximum throughput of at least 100 Mb/s, as measured at the medium access control data services access point. The IEEE 802.11n will provide both physical layer and MAC enhancements.
The use of FFT algorithms in the handling of data in the IEEE 802.11n transmission chain is generally useful, but known techniques of handling data using FFT algorithms pose certain limitations. The reception chain implemented in the 802.11n standard uses either a 64 points FFT or a 128 points FFT without any inherent flexibility therebetween. There is a need to address the flexibility-aspect of the 802.11n implementation.